In an IEEE (Institute of Electrical and Electronics Engineers) standard document for connection fault management (IEEE802.1ag), the maintenance domain (MD) and MA are described as follows: an MD is a network or a part of a network where failed connections can be managed, and all MEPs in an MD are on the same maintenance level; an MA is a subset of an MD and a set of MEPs that may communicate with each other in a certain service flow.
The existing IEEE802.1ag standard provides an explicit definition of an MA and specifies that all operation, administration and maintenance (OAM) tests must be carried out among MEPs in a certain MA. The MA integrity refers to: an MA must include necessary MEPs, and all MEPs in an MA are mated and may be OAM tested normally, i.e., no isolated and unmated MEP exists in an MA. If an isolated MEP exists in an MA, or an isolated MEP occurs because an MEP exits the MA which is integral, the OAM tests can not be performed for the isolated MEP, and the MA is not integral. Each MEP in an MA locally maintains an information table for all MEPs in the MA; the table is referred to as a local MEP table, which includes the following information: an MEP ID (identifier) and a corresponding source port of the MEP. However, the existing IEEE802.1ag standard does not provide the description or the solution on how to know whether an MA is integral and how to ensure MA integrity.